BLOCKING OF PAVLOVIAN CONDITIONING IN HUMANS

Despite the many demonstrations of blocking in animals, there is still little evidence of blocking with human subjects, which is problematic for general teaming and behavior theory. The purpose of this research was to examine blocking with human subjects using a design and behavi oral procedure (conditioned suppression) similar to those commonly use d in animal research. First, subjects learned an operant task. Later, they were instructed to suppress responding when a visual US was prese nted. Two Pavlovlian acquisition phases and a test phase occurred whil e the subjects were performing the operant task. In the first Pavlovia n phase, CS A predicted the US for the experimental group, but was unc orrelated with the US for the control group. In the second Pavlovian p hase, a compound CS AX predicted the US for both groups. At test, CS X was presented to all subjects and suppression ratios were assessed. E xperimental subjects suppressed responding in the presence of CS X les s than did control subjects, thereby demonstrating a blocking effect. This research, in demonstrating blocking in humans, adds to the known similarities in animal and human behavior. (C) 1997 Academic Press.